Famed Yankee Stadium beerman Steve Lazarus learned that the hard way after the longtime vendor was suspended for sharing a laugh with an arch-rival Boston Red Sox player.

Lazarus, who works as a stand-up comedian when he’s not slinging suds in the bleachers, was getting ready for the nightcap of last Sunday’s double-header when he had the exchange with Bosox relief pitcher Alfredo Aceves.

The vendor was standing with co-workers near a freight elevator on the terrace level when he heard the sound of cleats.

“I think we all looked over,” he said. “It’s rare that we hear [players] come by now.”

So the Bronx native and lifelong Yankee fan decided to have a little fun with Aceves, a former Bronx Bomber.

Lazarus, 53, who’s been hawking cold ones since he was 19, was summoned by a supervisor during the game.

“He said, ‘You were harassing the opposing team’s player.’

“I said, ‘Are you kidding?’ ”

After an investigation, Lazarus on Thursday was benched for the first two games — lucrative sell-outs — of the American League Division Series.

“They take my badge — this is only my 35th year, by the way — and they escort me out like a common criminal,” he told The Post. “To suspend me, when I did nothing?”

The beerman is foaming at the mouth over his treatment.

“The vendor is always wrong,” he fumed. “I’m so fed up.”

Lazarus, who wrote the book “The Pope and Me at Yankee Stadium,” said he frequently donates the proceeds of book sales or performs his stand-up to benefit charities that are associated with the Yankees.

And the suspension adds injury to insult — vendors’ incomes have already been slashed 50 percent this season by the introduction of waiter service in choice sections and by bad weather, he claims.

He could have earned $200 to $300 per playoff game and says he is so disgusted he might even skip tuning in on TV.